2000

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    Efficient Object-Based Hierarchical Radiosity Methods
    (Schäfer, Stephan, 2000-05-30) Schäfer, Stephan
    The efficient generation of photorealistic images is one of the main subjects in the field of computer graphics. In contrast to simple image generation which is directly supported by standard 3D graphics hardware, photorealistic image synthesis strongly adheres to the physics describing the flow of light in a given environment. By simulating the energy flow in a 3D scene global effects like shadows and inter-reflections can be rendered accurately. The hierarchical radiosity method is one way of computing the global illumination in a scene. Due to its limitation to purely diffuse surfaces solutions computed by this method are view independent and can be examined in real-time walkthroughs. Additionally, the physically based algorithm makes it well suited for lighting design and architectural visualization. The focus of this thesis is the application of object-oriented methods to the radiosity problem. By consequently keeping and using object information throughout all stages of the algorithms several contributions to the field of radiosity rendering could be made. By introducing a new meshing scheme, it is shown how curved objects can be treated efficiently by hierarchical radiosity algorithms. Using the same paradigm the radiosity computation can be distributed in a network of computers. A parallel implementation is presented that minimizes communication costs while obtaining an efficient speedup. Radiosity solutions for very large scenes became possible by the use of clustering algorithms. Groups of objects are combined to clusters to simulate the energy exchange on a higher abstraction level. It is shown how the clustering technique can be improved without loss in image quality by applying the same data-structure for both, the visibility computations and the efficient radiosity simulation.
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    Virtual Reality in Assembly Simulation - Collision Detection, Simulation Algorithms, and Interaction Techniques
    (Zachmann, Gabriel, July 2000) Zachmann, Gabriel
    In 1995, only a few VR systems were commercially available and a few more in the academic domain. None of these was mature at the time, nor had any of them been deployed in the field for everyday work. Some commercial and most academic systems were not so much a self-contained VR system, but rather a set of libraries which application programmers could build upon. In particular, VR was not ready for use for industry application. Problems persisted in the following areas (among others): electro-magnetic tracking, high-level specification of virtual environments, efficient interaction metaphors and frameworks, and real-time collision detection and response. This thesis has made contributions, to all of these areas. Almost all of the algorithms, applications, and frameworks presented in this thesis have been integrated into the VR system Virtual Design II, which has been developed by the department I am with, and which is now commercially available through the spin-off VRCom.